This invention relates in general to mountings for the road wheels of an automotive vehicles and, more particularly, to mountings in which a bearing race is embedded in an adjacent component.
The front wheels of an automotive vehicle must rotate about horizontal axes, and must also pivot about near vertical axes, the latter in order to steer the vehicle. To this end, the typical front wheel rotates on an antifriction bearing which is in turn fitted to a steering knuckle that forms part of the suspension system for the vehicle. The knuckle pivots about a near vertical axis on ball-and-socket joints.
In one arrangement, which finds widespread use in four wheel drive vehicles, the road wheel is bolted to a hub having a spindle which projects into the antifriction bearing. Indeed, the inner races of the bearing fit over the spindle (FIG. 1). The outer race, on the other hand, possesses a flange through which the bolts pass to secure it to the steering knuckle. Rolling elements fit between the inner and outer races where they run along raceways which are angulated to transfer both radial and thrust loads. The torque for driving the front wheels is transferred to the spindle on the hub through a constant velocity (CV) joint. Compared to the outer race of the bearing, the steering knuckle possesses considerable mass. It is usually formed from cast iron or cast steel. On the other hand, the bearing, including its flanged outer race, is formed from bearing quality steel which is considerably more expensive.
By reason of its flange, the outer race is larger than the outer races of more conventional bearings having the same load-carrying capacity. This requires a greater amount of bearing steel and machining. Indeed, the flange must undergo facing and the holes for the bolts need to be drilled. The steering knuckle, on the other hand, requires a machined bore to receive the outer race, and a machined face to accommodate the flange. Apart from that, it requires tapped holes for the bolts. Where the outer race has a flange, bolts which pass through the flange and thread into the knuckle serve this purpose.
Thus, the typical mounting for a front wheel at the location where the bearing is fitted to the steering knuckle possesses several parts and requires multiple machining operations. These are reflected in the cost of manufacturing the bearing and knuckle and in the expense of assembling it.
In other types of wheel mountings, the inner races remain stationary on a spindle or axle end and the outer races rotate with a hub to which the road wheel is attached. Typically, the hub has machined counter bores into which the outer races are fitted. Again the machinery requires time and expense.
The present invention resides in mounting for a road wheel of a vehicle which mounting includes two members, one of which is a hub to which a road wheel is attached and the other a suspension system component. It also includes an antifriction bearing, one race of which is embedded in one of the members as an insert. The invention further resides in a hub provided with a spindle and a suspension system component which fits around the spindle, it being formed as a metal casting. The hub rotates on a bearing including an inner race located around the spindle; an outer race embedded as an insert in the cast suspension system component, and rolling elements located between the two races. The invention also resides in the suspension system component formed as a steering knuckle with the outer race of the bearing being embedded in it as an insert.